Systems and methods of marker based direct integrity testing of membranes

ABSTRACT

The present disclosure relates, according to some embodiments, to methods of marker based direct integrity testing of at least one membrane comprising: (a) dosing a feed fluid of a loop with at least one marker comprising at least one challenge particle, the loop comprising: the feed fluid; a pump comprising an outlet stream; a membrane module comprising the at least one membrane and a membrane module outlet stream, wherein the membrane module is in fluid communication with the outlet stream; a marker recycle stream in fluid communication with the membrane module outlet stream and the pump; and a means to measure particle concentrations; (b) circulating the feed fluid through the membrane module at least once to produce a filtrate comprising a filtered at least one marker; (c) measuring a filtrate particle concentration of the filtered at least one filtered marker in the filtrate to produce a filtrate concentration measurement; and (d) calculating a log removal value from the filtrate concentration measurement and the feed concentration measurement; wherein the log removal value is less than about 3 μm.

FIELD OF THE DISCLOSURE

The present disclosure relates, in some embodiments, to systems andmethods for marker based direct integrity testing of membranesincluding, without limitation, a challenge test, a direct integritytest, and combinations thereof for membranes (e.g., ceramic membranes).

BACKGROUND OF THE DISCLOSURE

Interest in cleansed water, for example, as embodied in regulatoryguidance such as the Long Term 2 Enhanced Surface Water Treatment Rules(LT2ESWT or LT2), may call for parasite (e.g., Cryptosporidium, Giardia)sanitization/removal from surface water and/or surface water impactedwells. LT2 requirements outline verification methods for ensuringmembrane integrity for membranes that may be used for parasite removal.Membranes desirably may be free of breaches greater than 3 μm so thatthe membranes continue to filter Cryptosporidium oocysts that typicallyhave a diameter from about 4 μm to about 6 μm.

A challenge test in accordance with the LT2 guidance may be performed onfive separate membranes of a membrane system to quantify the log removalvalue (LRV) of a parasite or a surrogate organism or marker of similarsize, shape, and surface charge. These non-destructive challenge testsmust be performed on membrane systems daily to insure there is no breachin membrane integrity that is greater than 3 μm.

Challenge testing typically requires a membrane system to be shut down,which lowers productivity (e.g., water filtered) and increases expenses(e.g., added maintenance), but a direct integrity test (DIT) such as a“bubble-decay” method may be used while a membrane system is running.However, while a bubble-decay method may work on some membranes with lowporosity, this method does not work on ceramic membranes as the time ittakes for the air pressure to drop is too rapid to attain a precisionmeasurement necessary to measure a 3 μm or greater breach of themembrane.

SUMMARY

Accordingly, a need has arisen for improved methods of marker baseddirect integrity testing and of membranes. According to someembodiments, the present disclosure relates to a method of marker baseddirect integrity testing of at least one membrane comprising: (a) dosinga feed fluid of a loop with at least one marker comprising at least onechallenge particle, the loop comprising: the feed fluid; a pumpcomprising an outlet stream; a membrane module comprising the at leastone membrane and a membrane module outlet stream, wherein the membranemodule is in fluid communication with the outlet stream; a markerrecycle stream in fluid communication with the membrane module outletstream and the pump; and a means to measure particle concentrations; (b)circulating the feed fluid through the membrane module at least once toproduce a filtrate comprising a filtered at least one marker; (c)measuring a filtrate particle concentration of the filtered at least onefiltered marker in the filtrate to produce a filtrate concentrationmeasurement; and (d) determining from the filtrate concentrationmeasurement if a breach is present in the at least one membrane.

In some embodiments, the present disclosure relates to a method ofmarker based direct integrity testing of at least one membranecomprising: (a) isolating a loop from at least one portion of a waterpurification system, the loop comprising: a feed fluid; a pumpcomprising an outlet stream; a membrane module comprising the at leastone membrane and a membrane module outlet stream, wherein the membranemodule is in fluid communication with the outlet stream; a markerrecycle stream in fluid communication with the membrane module outletstream and the pump; and a means to measure particle concentrations; (b)dosing the feed fluid with at least one marker comprising at least onechallenge particle; (c) circulating the feed fluid through the membranemodule at least once to produce a filtrate comprising a filtered atleast one marker; (d) measuring a filtrate particle concentration of thefiltered at least one filtered marker in the filtrate to produce afiltrate concentration measurement; and (e) determining from thefiltrate concentration measurement if a breach is present in the atleast one membrane.

According to some embodiments, at least one membrane may comprise atleast one ceramic membrane. At least one ceramic membrane may beselected from the group consisting of TiO₂, ZrO₂, SiO₂, MnO₂, SiC, CuO,MgO, and Al₂O₃. Dosing a feed fluid of a loop with at least one markercomprising at least one challenge particle may comprise a concentrationof the at least one marker of about 6.5 log particle count. About 35% ofat least one challenge particle by mass contains particles having aparticle size from about 2 μm to about 3 μm. At least one challengeparticle is a TiO₂, wherein TiO₂ may be a P25 TiO₂. At least onemembrane module may be configured to operate at a flux from about 100liters/m²/h to about 2,000 liters/m²/h during a method of marker baseddirect integrity testing of a membrane. A method of marker based directintegrity testing of at least one membrane may comprise calculating alog removal value from the filtrate concentration measurement, whereinthe log removal value is less than about 3.

According to some embodiments, a marker based direct integrity of atleast one membrane testing system may comprise: (a) a feed fluidcomprising at least one marker, the at least one marker comprising atleast one challenge particle; (b) a loop comprising: a pump comprisingan outlet stream; a membrane module comprising the at least one membraneand a membrane module outlet stream, wherein the membrane module is influid communication with the outlet stream; and a marker recycle streamin fluid communication with the membrane module outlet stream and thepump; and (c) a particle counter, wherein marker based direct integritymembrane testing system is configured to measure a log removal value.

In some embodiments, a marker based direct integrity membrane system maycomprise a high solids contact reactor tank in fluid communication influid communication with the pump; an inlet configured to receive aninfluent fluid, wherein the inlet is in fluid communication with thehigh solids contact reactor tank; an influent turbidity measurementdevice; an exit stream in fluid communication with the membrane module;and a permeate turbidity measurement device in fluid communication withthe exit stream. A system may comprise a positive displacement pump.

In some embodiments, a means for measuring a particle concentration maycomprise a particle counter. A means for measure a particle may comprisea turbidity measurement device.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the disclosure may be understood by referring, inpart, to the present disclosure and the accompanying drawings, wherein:

FIG. 1 illustrates an electron micrograph of Cryptosporidium accordingto a specific example embodiment of the disclosure;

FIG. 2 illustrates a marker based membrane direct integrity testingsystem according to a specific example embodiment of the disclosure; and

FIG. 3 illustrates a particle counter system according to a specificexample embodiment of the disclosure.

DETAILED DESCRIPTION

The present disclosure relates, in some embodiments, to systems andmethods of marker based direct integrity testing of membranes. Membranesmay be used in water purification processes and/or fluid filtrationprocesses, wherein a feed fluid may come into contact with a membrane,thereby forming a filtrate and a retentate. Various factors may dictateseparation patterns such as membrane pore size and separation drivingforce. Membrane integrity must be maintained so that a consistentmembrane pore size and/or separation driving force may desirably filtercontaminants such as parasites (e.g., Cryptosporidium) and bacteria(e.g., fecal coliform). Methods of marker based membrane directintegrity testing, and systems thereof, may analyze membrane integrityin a non-destructive manner. Membranes comprising a desirable thresholdof integrity may be continued to be used, whereas membranes that do notcomprise a desirable threshold of integrity may be replaces so thatcontaminants are reliably desirably filtered.

Systems and methods of marker based membrane direct integrity testingcomprise a challenge testing, a direct integrity test, and a combinationthereof. A marker based membrane direct integrity test may be performedin place of a separate challenge test and/or a direct integrity test.Performing a marker based membrane direct integrity testing may notrequire a system to be shut down. For example, a marker based membranedirect integrity test may be performed while a system is operating(i.e., filtering and/or purifying fluid) at full volume and/or speedcapacity. A marker based membrane direct integrity test may be performedwhile a system is not running A system or method of marker basedmembrane direct integrity testing may be performed on membranes of anykind, including ceramic membranes.

Methods of Marker Based Membrane Direct Integrity Testing

According to some embodiments, methods of marker based membrane directintegrity testing comprises marker based direct integrity testing of atleast one membrane. A method may comprise dosing a feed fluid of a loopwith at least one marker, circulating the feed fluid through themembrane module at least once to produce a filtrate comprising afiltered at least one marker; measuring a filtrate particleconcentration of the filtered at least one filtered marker in thefiltrate to produce a filtrate concentration measurement; measuring afeed particle concentration of the at least one marker in the feed fluidto produce a feed concentration measurement; and calculating a logremoval value from the filtrate concentration measurement and the feedconcentration measurement.

Dosing a feed fluid of a loop with at least one marker may comprisedosing the feed fluid to achieve an log particle count of the at leastone marker of about 2.5, or of about 3, or of about 3.5, or of about 4,or of about 4.5, or of about 5, or of about 5.5, or of about 6, or ofabout 6.5, or of about 7, or of about 7.5, or of about 8, or of about8.5, or of about 9. A log particle count may be measured and calculatedby a particle counter that may sample a feed fluid to measure andcalculate a log particle count.

According to some embodiments, a loop may comprise a feed fluid; a pumpcomprising an outlet stream; a membrane module comprising at least onemembrane and a membrane module outlet. A loop may also comprise a markerrecycle stream in fluid communication with a membrane module outletstream and a pump. A loop may also comprise a means to measure particleconcentrations. A loop may be a closed loop and/or an open loop.

Circulating a feed fluid through a membrane module at least once maycomprise circulating the feed fluid through a loop at least once.Circulating may comprise a continuous and/or singular circulation.Singular circulation may comprise a temporal and/or volumetriccirculation.

Methods of marker based membrane direct integrity testing may beperformed on a water purification system. In some embodiments, a waterpurification may be stopped (i.e., discontinued active fluidpurification) to perform a marker based membrane direct integrity test.A water purification may continue to be active (i.e., continued activefluid purification) to perform a marker based membrane direct integritytest. A method of marker based membrane direct integrity testing may beperformed wherein at least one membrane module is configured to operateat a flux from about 100 liters/m²/h to about 2,000 liters/m²/h duringthe method of marker based direct integrity testing of a membrane. Amethod of marker based membrane direct integrity testing may beperformed, wherein at least one membrane module is configured to operateat a flux of about 100 liters/m²/h, or of about 200 liters/m²/h, or ofabout 400 liters/m²/h, or of about 600 liters/m²/h, or of about 800liters/m²/h, or of about 1,000 liters/m²/h, or of about 1,200liters/m²/h, or of about 1,400 liters/m²/h, or of about 1,600liters/m²/h, or of about 1,800 liters/m²/h, or of about 2,000liters/m²/h. A method of marker based membrane direct integrity testingmay be performed, wherein at least one membrane module is configured tooperate at a flux of about 2000 liters/m²/h or less during the method ofmarker based direct integrity testing of a membrane.

Methods of marker based membrane direct integrity testing may beperformed on at least one membrane. Methods of marker based membranedirect integrity testing may be performed on more than one membrane inat least one series. Methods of marker based membrane direct integritytesting may be performed on at more than one membrane in parallel.Methods of marker based membrane direct integrity testing may beperformed on more than one membrane in series and/or parallel, or acombination thereof.

Methods of marker based membrane direct integrity testing may compriseisolating a loop from at least one portion of a water purificationsystem. Isolating a loop may comprise any type of valve (e.g., shut-offvalve), seal, hatch, and/or physical separation. A valve may comprise astop valve, a straight valve, a gate valve, a ball valve, a butterflyvalve, a disc valve, a choke valve, a check valve, a globe valve, apinch valve, a thermal expansion valve, a sampling valve, a pistonvalve, a diaphragm valve, and combinations thereof. Isolating a loopfrom at least one portion of a water purification system may bepermanent and/or temporary.

Removal Efficiency and Membrane Integrity

In some embodiments, a method of marker based membrane direct integritytesting system may comprise a removal efficiency. A removal efficiencymay be inversely proportional to membrane integrity. A membrane with adesirable removal efficiency may have less membrane integrity than amembrane with a less than desirable removal efficiency. A removalefficiency may be expressed as a log removal value (LRV). An LRV may becalculated as LRV=log(C_(f))−log(C_(p)), wherein Cf may be a feedconcentration of at least one challenge particle and C_(p) may be afiltrate concentration of the at least one challenge particle. Cf may bea dose concentration of at least one challenge particle. A doseconcentration may be calculated using a formula developed throughtesting various concentrations at various volumes (e.g., calibrationcurve). If a challenge particle is not detected in a filtrate, a termC_(p) may be set equal to a detection limit for calculating a LRV. AnLRV may be calculated for each membrane module evaluated during thechallenge test. A membrane module may contain at least one membrane. Itwill be appreciated by those of ordinary skill in the art having thebenefit of the instant disclosure that a membrane may be said to have abreach when it comprises an undesirable opening (e.g., tear, pore, orother aperture) that traverses the working matrix of the membrane and islarger (e.g., substantially larger) than the maximum openings otherwisepresent in the membrane. A breach may compromise a membrane's ability torestrict movement of particles above a desired threshold size.

In some embodiments, presence of a breach may be determined by measuringa filtrate particle concentration of a filtered particle (e.g., marker).A breach may be determined by assessing whether a challenge particle ispresent at or above a threshold value of a particle concentration in avolume of a fluid, an LRV, or a combination thereof. A threshold valuemay be determined empirically from a presence or an absence of afiltered particle measured from a volume of a fluid. A threshold valuemay also be set based on calculated values. Reaching or exceeding athreshold value of particles of various sizes and shapes may indicate apresence of a breach of various sizes. For example, presence of athreshold value of a first particle or a first contaminant may indicatea breach of about 3 μm, wherein presence of a threshold value of asecond particle or a second contaminant may indicate a breach of about 4μm. In some embodiments, presence of a challenge particle at or above afirst concentration may indicate a 3 μm breach and presence of thechallenge particle at or above a second concentration may indicate a 4μm breach. A challenge particle may comprise a contaminant or may be aproxy for a contaminant. As indicated, a breach may be a factordetermined by particle or contaminant size, but may also depend onfilter characteristics comprising composition, porosity, packing,dimensions, and mesh. A breach determination by measuring a filteredparticle concentration of a fluid may also be affected by whichmeasuring instrument is used, such as whether a particle counter,turbidity measurement device, or combination thereof is used. Forexample, a particle counter or a turbidity measurement device may betuned for various sensitivity and detection ranges, which may providefor variations in breach detection through a measurement of a filteredparticle concentration from a volume of filtered fluid.

Marker Based Membrane Direct Integrity Testing System

According to some embodiments, a marker based direct integrity membranetesting system may be configured to measure a log removal value. Amarker based direct integrity membrane testing system may comprising afeed fluid comprising at least one marker, the at least one markercomprising at least one challenge particle. A marker based directintegrity membrane testing system may comprise a loop comprising a pumpcomprising an outlet stream; a membrane module comprising at least onemembrane and membrane module outlet stream, wherein the membrane moduleis in fluid communication with the outlet stream; a marker recyclestream in fluid communication with the membrane module outlet stream andthe pump; and a particle counter. A membrane module may comprise atleast one membrane. At least one membrane may be a ceramic membrane.

A marker based direct integrity membrane testing system may comprise ahigh solids contact reactor tank in fluid communication in fluidcommunication with a pump; an inlet configured to receive an influentfluid, wherein the inlet is in fluid communication with the high solidscontact reactor tank. A marker based direct integrity membrane testingsystem may comprise an influent turbidity measurement device; an exitstream in fluid communication with a membrane module; and a permeateturbidity measurement device in fluid communication with the exitstream.

Challenge Particle

In some embodiments, a marker based membrane direct integrity testingsystem may comprise at least one challenge particle (i.e., marker).According to some embodiments, at least one challenge particle may serveas a surrogate for a parasite (e.g., Cryptosporidium and Giardia) and acoliform bacteria (e.g., fecal coliform). At least one challengeparticle may have a generally spherical shape (e.g., similar toCryptosporidium). At least one challenge particle may have a comparableparticle size that is similar to Cryptosporidium. At least one challengeparticle may also have a neutral particle surface charge, which may besimilar to Cryptosporidium. At least one challenge particle may beconfigured to be a surrogate for fecal coliform, wherein fecal coliformhas a size range from about 1 μm to about 4 μm. At least one challengeparticle may be configured to be a surrogate for Cryptosporidium,wherein Cryptosporidium has a size range from about 3 μm to about 7 μm.At least one challenge particle may be configured to be a surrogate forGiardia, wherein Giardia has a size range from about 7 μm to about 15μm. At least one challenge particle may be a marker. At least one markermay be made in a pre-mixed solution and stored in a separate tank.Dosing a feed fluid of a loop with at least one marker may be done by apositive displacement pump. A positive displacement pump may beconfigured to dose a specific volume and/or mass of at least one marker.

At least one challenge particle may have a particle size from about 0.5μm to about 7 μm. At least one challenge particle may have a particlesize of less than about 7 μm, or less than about 6 μm, or less thanabout 5.5 μm, or less than about 5 μm, or less than about 4.5 μm, orless than about 4 μm, or less than about 3.5 μm, or less than about 3μm, or less than about 2.5 μm, or less than about 2 μm, or less thanabout 1.5 μm, or less than about 1 μm, or less than about 0.5 μm. Atleast one challenge particle may have a particle size of about 7 μm, orof about 6 μm, or of about 5.5 μm, or of about 5 μm, or of about 4.5 μm,or of about 4 μm, or of about 3.5 μm, or of about 3 μm, or of about 2.5μm, or of about 2 μm, or of about 1.5 μm, or of about 1 μm, or of about0.5 μm. At least one challenge particle may have a particle size fromabout 0.5 μm to about 7 μm, or from about 1 μm to about 6 μm, or fromabout 2 μm to about 4 μm, or from about 2.5 μm to about 3.5 μm, or fromabout 0.5 μm to about 7 μm, or from about 0.5 μm to about 6 μm, or fromabout 0.5 μm to about 5 μm, or from about 0.5 μm to about 4 μm, or fromabout 0.5 μm to about 3 μm, or from about 0.5 μm to about 2 μm, or fromabout 0.5 μm to about 1 μm.

In some embodiments, at least one challenge particle may have a neutralsurface charge. At least one challenge particle may have a neutralsurface charge at a neutral pH (i.e., pH=about 7). At least onechallenge particle may have a neutral surface charge at a pH of about3.5, or of about 4, or of about 4.5, or of about 5, or of about 5.5, orof about 6, or of about 6.5, or of about 7, or of about 7.5, or of about8, or of about 8.5, or of about 9. At least one challenge particle mayhave a neutral surface charge at a pH from about 3.9 to about 8.2.

According to some embodiments, at least one challenge particle may beselected from the group consisting of TiO2, ZrO2, SiO₂, MnO2, SiC, CuO,MgO, and Al₂O₃. At least one challenge particle may be TiO2. At leastone challenge particle may be nanoparticle type P25 30 TiO2. Ananoparticle type P25 TiO₂ may have about 27 to about 36% by mass ofparticles having a particle size of between about 2 μm and about 3 μm. Ananoparticle type P25 TiO2 may have about 25 to about 40% by mass ofparticles having a particle size of between about 2 μm and about 3 μm. Ananoparticle type P25 TiO₂ may have about 35.8% by mass of particleshaving a particle size of between about 2 μm and about 3 μm. At leastone production membrane may be subjected to a marker based membranedirect integrity test prior to delivery of the at least one membrane andan integrity of at least one membrane may be verified daily duringoperations. An at least one challenge particle (e.g., marker) coststructure may comprise about $0.40/day/millions of gallons per day) fora marker based membrane direct integrity test. A single charge of TiO₂may be used on a process that more than one membrane and/or membranemodules in a series. A single charge of TiO₂ may be used on a processthat including two membranes and/or membrane modules in a series.

Particle Counter

In some embodiments, a marker based membrane direct integrity testingsystem may comprise a particle counter. A particle counter mayindirectly or directly measure the size and count of particles in avolume of a fluid. For example, a particle counter may indirectly ordirectly measure the concentration of particles of a fluid. A particlecounter may provide for a means to measure a particle (e.g., challengeparticle) concentration. In some embodiments, a particle counter maymeasure a concentration of a challenge particle contained in a fluid. Aparticle counter may also be configured to measure for a removal offluid contaminants (e.g., Giardia and Cryptosporidium). A particlecounter may sample fluid from a system while the system is running(e.g., actively filtering fluid). A particle counter may be used toperform a marker based membrane direct integrity test for more than onemembrane and/or membrane module. In some embodiments, a false negativemay be observed by a particle counter if air bubbles in a permeate fluidare measured as particles. A particle counter may sample a feed fluidand/or a filtrate fluid to measure and calculate a log particle count. Aparticle counter may sample a feed fluid and/or a filtrate fluid while awater purification system is operating and/or when the waterpurification system is not operating.

Turbidity Measurement Device

A marker based membrane direct integrity testing system may comprise aturbidity measurement device (i.e., turbidity meter). A turbiditymeasurement device may measure the cloudiness or haziness of a fluidthat may be caused by individual particles (i.e., turbidity). Turbiditymay be measured in nephelometric turbidity units (NTU). A turbiditymeasurement device may be configured to measure the turbidity of aninfluent fluid as well as a permeate fluid. In some embodiments, aturbidity measurement device may directly or indirectly measure a numberof particles in a volume of a fluid. A turbidity measurement device mayprovide for a means to measure a particle concentration of a fluid. Aturbidity measurement device may be used to measure the concentration ofat least one marker. A direct correlation between turbidity and aconcentration of at least one marker may be established.

Membrane Module

The present disclosure relates, in some embodiments, to a membranemodule comprising at least one membrane, an interior membrane modulecavity, and a membrane module outlet in fluid communication with theinterior membrane module cavity. A membrane module may receive fluidfrom a pump through a pump outlet stream. A membrane module may have amarker recycle stream. A membrane module may have any desired shape. Insome embodiments, a membrane module may have a generally cylindricalshape defining a central longitudinal axis and a cavity spanning itslength. For example, up to all sections perpendicular to a centralmembrane module axis may have a generally annular shape. A membranemodule may have a hollow, generally cylindrical shape, a first end and asecond end according to some embodiments. Each end may define anaperture sized and/or shaped to receive a ceramic element interface.

A membrane module may have any desired dimensions. According to someembodiments, a membrane module may be from about 10 cm to about 5 mlong, from about 50 cm to about 5 m long, from about 1 m to about 3 mlong, and/or combinations thereof. A section taken perpendicular to thelongitudinal axis may have a longest dimension (e.g., diagonal ordiameter) from about 2 cm to about 30 cm in diameter, from about 2 cm toabout 20 cm in diameter, from about 5 cm to about 20 cm in diameter,from about 5 cm to about 15 cm in diameter, from about 10 cm to about 45cm in diameter, and/or combinations thereof. A membrane module may beconfigured for cross-flow filtration (i.e., tangential filtration)and/or dead-end filtration. A membrane module may be configured topermit outside-in filtration and/or inside-out filtration.

Ceramic Membrane

A ceramic element (also called an element) may comprise, according tosome embodiments, a filter of any desired size, shape, or composition.For example, a ceramic element may comprise a generally tubular filter(e.g., a ceramic filter). A ceramic element may include any desiredfilter or filter material. For example, a ceramic element may comprise afilter having one or more organic polymers and/or one or more ceramicmaterials. Examples of filters (e.g., ceramic membranes) may includemicrofiltration filters, ultrafiltration filters, nanofiltrationfilters, antimicrobial filters, maintenance-free filters, andcombinations thereof. A filter may comprise an antimicrobial agent. Forexample, a ceramic filter may comprise silver (e.g., an impregnated,non-leachable silver). In some embodiments, a ceramic element mayexclude a filter (e.g., where the element adsorbs ions). A ceramicmembrane may be filter through cross-flow filtration (i.e., tangentialfiltration) and/or dead-end filtration. A ceramic membrane may beconfigured for outside-in filtration and/or inside-out filtration.

In some embodiments, ceramic filters may be durable (e.g., more durablethan organic polymer filters). For example, ceramic filters may beresistant to mechanical damage, solvents, and/or microbes. Examplemetrics of performance and/or resistance may be the degree of filtrationprovided for one or more contaminants, conductivity, usable lifespan,and/or combinations thereof. Desired performance and/or resistance maybe expressed as a fraction (e.g., percentage) compared in the presenceor absence of challenge, relative to another membrane, or against athreshold or target value.

In some embodiments, a ceramic membrane may comprise a ceramic elementand a filter layer. For example, a ceramic membrane may comprise afiltration layer (e.g., a membrane) having smaller pores and anunderlying base or substrate having larger pores. A ceramic membrane mayinclude a filter layer only inside the channels and an epoxy coatingsealing the end face. According to some embodiments, a filtration layermay instead cover an interior surface, an end face, and/or an exteriorsurface. For example, a filtration layer may define, be coextensivewith, and/or cover a contaminated media facing surface of an element. Aceramic filtration layer may line the interior surface (e.g., channels),wrap around the face of the element, and extend a portion of the waydown the outside of the element (at each end). A base may define, becoextensive with, and/or cover a permeate facing surface.

An elongate ceramic element may have a cross-section (e.g., a sectionperpendicular to the central longitudinal axis) with any desired regularor irregular geometric shape. For example, an element cross-section mayhave a shape selected from generally circular, generally elliptical,generally polygonal (e.g., hexagonal), and/or combinations thereof. Anelongate element may have a central axis with one or more channels alongthe length of the element and generally parallel to the axis.

A ceramic element may have any desired dimensions. According to someembodiments, an elongate element may be from about 10 cm to about 5 mlong, from about 50 cm to about 5 m long, from about 1 m to about 3 mlong, and/or combinations thereof. A section taken perpendicular to thelongitudinal axis (e.g., “diameter”) may be from about 2 cm to about 30cm in diameter, from about 2 cm to about 20 cm in diameter, from about 5cm to about 20 cm in diameter, from about 5 cm to about 15 cm indiameter, from about 10 cm to about 45 cm in diameter, and/orcombinations thereof. An element may comprise one or more longitudinalchannels. For example, an element may have about 37 channels arranged in7 rows with 4-7 channels in each row. An element may have about 19channels arranged in 5 rows with 3-5 channels in each row. Each channelmay independently have any desired shape and/or dimension. In someembodiments, a channel may have a generally circular shape with a radiusfrom about 1 mm to about 15 cm, from about 2 mm to about 10 cm, fromabout 5 mm to about 5 cm, from about 1 cm to about 5 cm, and/orcombinations thereof.

A ceramic element (e.g., a substrate) may comprise up to about 100%(w/w) silicon carbide. Silicon carbide (SiC) is a semi-conductormaterial, meaning that it has electrical conductivity that ranks betweenthat of an insulator and a metal. A semiconductor may change itselectrical conductance with the addition of a dopant. For SiC, dopantswhich increase electrical conductivity may include, for example, boron,aluminum and nitrogen.

A ceramic element may be configured, in some embodiments, to selectivelyfilter a fluid with respect to the sizes of the solids (e.g., dissolvedsolids, suspended solids) present. For example, a ceramic element mayinclude a membrane having pores sized to separate, exclude, and/orremove contaminants (e.g., particles) on the basis of their size.According to some embodiments, a ceramic element may be configured toseparate, exclude, and/or remove contaminants with respect to theircharge. For example, a ceramic element may be configured to reduce thenumber of charged contaminants in a fluid (e.g., a contaminated media, apermeate produced in a prior purification step). A ceramic element maycomprise one more polar and/or charged components. A ceramic element maycomprise, in some embodiments, one or more components that may becomecharged upon application of a current. Charged contaminants may beseparated, excluded, and/or removed by adsorption to an oppositelycharged substrate material as fluid continues through the elementaccording to some embodiments.

In some embodiments, a marker based membrane direct integrity testingsystem may comprise an inside out style membrane. A marker basedmembrane direct integrity testing system may also comprise membraneplates.

High Solids Contact Reactor Tank

In some embodiments, a marker based membrane direct integrity testingsystem may comprise a high solids contact reactor tank. A high solidscontact reactor tank may comprise, in some embodiments, an inlet and aceramic element interface, according to some embodiments. A high solidscontact reactor tank may comprise an interior cavity. An interior cavitymay have any desired size and/or any desired shape. For example, acavity may have a rounded and/or generally dome shape. A high solidscontact reactor tank may have an outer perimeter and/or circumference.In some embodiments an outer perimeter and/or circumference may beconfigured as and/or define a high solids contact reactor tank flange. Ahigh solids contact reactor tank flange may be configured to engage apermeate chamber (e.g., a permeate chamber comprising a similar or matedflange). In some embodiments, a high solids contact reactor tank flangemay comprise a channel for a gasket, O-ring, or other seal. A highsolids contact reactor tank channel may be positioned on one face of aflange and/or substantially parallel to an outer perimeter and/orcircumference in some embodiments

According to some embodiments, a high solids contact reactor tank mayhave one or more inlets and/or one or more outlets. For example, a highsolids contact reactor tank may have a ceramic element interfacecomprising one or more outlets. Each outlet may be configured to engagea ceramic element, for example, with a substantially fluid-tight seal.In some embodiments, an outlet may have any desired shape (e.g.,cylindrical, conical, frustoconical). All high solids contact reactortank outlets may be positioned in an interface and/or inside a highsolids contact reactor tank channel

A high solids contact reactor tank and/or a concentrate chamber may haveany desired dimensions. According to some embodiments, a high solidscontact reactor tank may have a length from about 100 cm to about 1,000cm. A section taken perpendicular to a chamber's longitudinal axis mayhave a longest dimension (e.g., diagonal or diameter) from about 100 cmto about 600 cm in diameter.

Pump

According to some embodiments, a marker based membrane direct integritytesting system may comprise a pump. A pump may be disposed between aconcentrate tank and a filtration unit. A pump may be in fluidcommunication with an exit stream of a concentrate tank. A pump may beconfigured to regulate flow rate of a concentrated fluid from theconcentrate tank to a filtration unit to create a desired cross flowthrough the filtration unit, and provide sufficient mixing in theconcentrate tank.

Various types of pump may be used without departing from the descriptionherein. In some embodiments, a pump may be a turbomolecular, centrifugalpump, vacuum pump, horizontal pump, or screw pump.

Inlet

In some embodiments, a marker based membrane direct integrity testingsystem may comprise an inlet. In some embodiments, an inlet may comprisea pipe, tube, or stream. An inlet, pipe or tube may comprise particularmaterials and may have a particular length or diameter. An inlet may beconfigured to receive an influent fluid. An influent fluid may have aparticular flow rate or a flow rate of a contaminated fluid therein.Dimensions and specifications such as particular materials, length anddiameter of pipes, and flow rates may be varied without departing fromthe description herein.

Specific Example Embodiments

FIG. 1 illustrates an electron micrograph of Cryptosporidium accordingto a specific example embodiment of the disclosure. FIG. 1 illustrates aspherical (e.g., sphere, spheroid) shape and a relative size ofCryptosporidium, wherein the Cryptosporidium oocysts may have a diameterfrom about 4 μm to about 6 μm. A challenge particle may serve as asurrogate for Cryptosporidium and may have a spherical structure andsize that is similar to Cryptosporidium. A challenge particle may have aparticle size or a diameter from about 1 μm to about 2 μm, which may bea smaller diameter than Cryptosporidium.

A specific example embodiment of a marker based membrane directintegrity testing system is illustrated in FIG. 2. FIG. 2 illustrates amarker based membrane direct integrity testing system 200 according to aspecific example embodiment of the disclosure. A system 200 for markerbased direct integrity testing of membranes may comprise an inlet 202, ahigh solids contact reactor tank 216, a high solids contact reactor tankrecycle stream 224, an influent turbidity measurement device 212, apermeate turbidity measurement device 228, a pump 220 (e.g., turbomolecular pump), a membrane module 218, a marker recycle stream 208, aparticle counter 206, a pump outlet stream 222, a recycle stream 226, amembrane module outlet stream 210, and an exit stream 204. System 200may be configured for contaminant removal. System 200 may be configuredfor a marker based method of DIT. A positive pressure pump may beconfigured to dose a system 200 with at least one marker. An inlet 202may be in fluid communication with a high solids contact reactor tank216 and an influent turbidity measurement device 212. A high solidscontact reactor tank 216 may receive fluid from an inlet 202. A highsolids contact reactor tank 216 may comprise an about 200 gallon tankand may comprise an about 6 ft (i.e., 1.8288 m) diameter.

A high solids contact reactor tank 216 may be in fluid communicationwith a pump 220, wherein the pump 220 may be configured to drive,discharge, and/or regulate flow of a fluid to a pump outlet stream 204that is in fluid communication with a membrane module 218. A membranemodule 218 may comprise a marker recycle stream that is in fluidcommunication with a pump 220 and a high solids contact reactor tankrecycle stream 224. A membrane module may comprise at least one ceramicmembrane. A membrane module may also comprise a membrane module outletstream 210 that is in fluid communication with an outlet 204 and arecycle stream 226. A particle counter 206 may be in fluid communicationwith a recycle stream 226, wherein the particle counter 206 may samplefluid from the recycle stream 226. A particle counter 206 may be influid communication with a membrane module outlet stream 210. A permeateturbidity measurement device 228 may be in fluid communication with anoutlet 204, wherein the permeate turbidity measurement device 228 maysample fluid from the outlet 204. A pump 220 may receive fluid from arecycle stream and/or a marker recycle stream 208. A marker recyclestream 208 may receive fluid from a high solids contact reactor tankrecycle stream 216.

A specific example embodiment of a marker based membrane directintegrity testing system is illustrated in FIG. 3. FIG. 3 illustrates aparticle counter 305 set-up according to a specific example embodimentof the disclosure. A particle counter 305 may comprise an inlet 335, afirst drain 330, a mesh screen 325 (e.g., 80 mesh screen), a flowtransducer 310, a particle sensor 345, a shepherds crook 315, an airvent vacuum breaker 320, and a second drain 340. A particle counter 305may comprise a first inlet 335 in fluid communication with a first drain330, and a mesh 325. A mesh 325 may be in fluid communication with aflow transducer 310, and a particle sensor 345. A particle sensor 345may be in fluid communication with a shepherd's crook 315. A shepherd'scrook 315 may be in fluid communication with an air vent vacuum break320 and a second drain 340.

As will be understood by those skilled in the art who have the benefitof the instant disclosure, other equivalent or alternative compositions,devices, methods, and systems for marker based direct integrity testingof a membrane can be envisioned without departing from the descriptioncontained herein. Accordingly, the manner of carrying out the disclosureas shown and described is to be construed as illustrative only.

Persons skilled in the art may make various changes in the shape, size,number, and/or arrangement of parts without departing from the scope ofthe instant disclosure. For example, the position and number of inlets,apertures, filters, gaskets, valves, pumps, sensors, and/or outlets maybe varied. In some embodiments, filters, seal gaskets, and/or filtrationassemblies may be interchangeable. Interchangeability may allow the sizeand/or kind of contaminates to be custom adjusted (e.g., by varying orselecting the pore size and/or kind of filter used). In addition, thesize of a device and/or system may be scaled up (e.g., to be used forhigh throughput commercial or municipal fluid filtration applications)or down (e.g., to be used for lower throughput household or researchapplications) to suit the needs and/or desires of a practitioner. Eachdisclosed method and method step may be performed in association withany other disclosed method or method step and in any order according tosome embodiments. Where the verb “may” appears, it is intended to conveyan optional and/or permissive condition, but its use is not intended tosuggest any lack of operability unless otherwise indicated. Personsskilled in the art may make various changes in methods of preparing andusing a composition, device, and/or system of the disclosure. Forexample, a composition, device, and/or system may be prepared and orused as appropriate for animals and/or humans (e.g., with regard tosanitary, infectivity, safety, toxicity, biometric, and otherconsiderations). Elements, compositions, devices, systems, methods, andmethod steps not recited may be included or excluded as desired orrequired.

Also, where ranges have been provided, the disclosed endpoints may betreated as exact and/or approximations as desired or demanded by theparticular embodiment. Where the endpoints are approximate, the degreeof flexibility may vary in proportion to the order of magnitude of therange. For example, on one hand, a range endpoint of about 50 in thecontext of a range of about 5 to about 50 may include 50.5, but not 52.5or 55 and, on the other hand, a range endpoint of about 50 in thecontext of a range of about 0.5 to about 50 may include 55, but not 60or 75. In addition, it may be desirable, in some embodiments, to mix andmatch range endpoints. Also, in some embodiments, each figure disclosed(e.g., in one or more of the examples, tables, and/or drawings) may formthe basis of a range (e.g., depicted value+/−about 10%, depictedvalue+/−about 50%, depicted value+/−about 100%) and/or a range endpoint.With respect to the former, a value of 50 depicted in an example, table,and/or drawing may form the basis of a range of, for example, about 45to about 55, about 25 to about 100, and/or about 0 to about 100.Disclosed percentages are weight percentages except where indicatedotherwise.

All or a portion of a device and/or system for marker based directintegrity testing of a membrane may be configured and arranged to bedisposable, serviceable, interchangeable, and/or replaceable. Theseequivalents and alternatives along with obvious changes andmodifications are intended to be included within the scope of thepresent disclosure. Accordingly, the foregoing disclosure is intended tobe illustrative, but not limiting, of the scope of the disclosure asillustrated by the appended claims.

The title, abstract, background, and headings are provided in compliancewith regulations and/or for the convenience of the reader. They includeno admissions as to the scope and content of prior art and nolimitations applicable to all disclosed embodiments.

EXAMPLES

Some specific example embodiments of the disclosure may be illustratedby one or more of the examples provided herein.

Example 1: Marker Based Direct Integrity Testing System

A marker based direct integrity testing system may be configured asshown in Table 1. A marker based direct integrity testing system may beset up for testing and laboratory work. A marker based direct integritytesting system may be designed and constructed as a full scale unit.

TABLE 1 Marker Based Direct Integrity Testing System SpecificationParameter Value Dimensions Ceramic Element Length 1020 mm CeramicElement Surface Area 0.569 m² Filtration Flow Direction Inside OutOperating Limits Maximum certified flux at 20° C. 2000 LMH Maximumcertified flow at 20° C. 19 L/min Operating temperature range No LimitsMaximum feed pressure 350 psi Maximum transmembrane pressure 50 psiOperating pH range 0-14 Maximum chlorine tolerance No limitsManufacturing NDPT Method Marker Style MIT Quality Control ReleaseValue >4 Log Removal Value

Example 2: Marker Size and Distribution

A feed to a particle counter may be connected downstream of a loop pumpand upstream of a membrane module on the concentrate side of themembrane. A baseline or initial count was obtained (before TiO₂ wasadded). The initial count consists of residual TiO₂ from previous tests.

After a baseline count of about 130,000 counts per 100 mL was obtainedon the concentrate side of the membrane (no TiO₂ addition) TiO₂ wasadded batch wise (Table 2) to the feed tank and allowed to mix as perthe test methodology. As shown in the table above, 2.1 ppm of TiO₂created a total particle count of 5.71 log particles at 2 to <3 μm.Also, the percentage of particles between 2 and 3 micron ranged from35.8%-27.3%.

TABLE 2 Particle Count/100 mL vs TiO₂ concentration Particle Size TiO₂Concentration (μm) 0 0.25 ppm 1 ppm 1.5 ppm 2.1 ppm  2+ 130000 3180001045000 1438000 1860000  3+ 80800 204000 712000 1023900 1353000  5+23700 50900 206500 321000 445200  7+ 11800 20000 90900 145000 200000 10+3600 3900 19800 30900 44000 15+ 1000 900 4300 6000 7800 20+ 300 200 600500 800 25+ 0 0 100 200 100 Total 130000 318000 1045000 1438000 1860000Total 2 < 3 49200 114000 333000 414100 507000 log 2 to <3 4.69 5.06 5.525.62 5.71 % 2 to <3 37.8% 35.8% 31.9% 28.8% 27.3%

The test was repeated with another batch of TiO₂. The test data is foundin Table 3.

TABLE 3 Particle Count/100 mL vs TiO₂ concentration Particle Size TiO₂Concentration (μm) 0 1 ppm 1.5 ppm 2.1 ppm  2+ 228500 1080000 14320001782000  3+ 139900 721000 987000 1271000  5+ 3400 189000 273500 370000 7+ 14000 72800 105800 145200 10+ 2700 12200 15000 21900 15+ 400 25003000 4100 20+ 100 500 600 800 25+ 100 100 200 200 Total 228500 10800001432000 1782000 Total 2 < 3 88600 359000 445000 511000 log 2 to <3 4.955.56 5.65 5.71 % 2 to <3 38.8% 33.2% 31.1% 28.7%

With increased TiO₂ loading the percentage of particles in the 2-3micron range declined above 1.25 ppm concentration. The particle countermanufacturer advised that at concentrations above 1,000,000 counts/100mL some shadowing of particles occurs providing counts lower than whatis actually present. (i.e., Upper Range of the Sensor).

To mitigate this error for the calculation of how much TiO₂ is requiredto achieve 6.5 Log particles/100 ml, the results from the smallestaddition of TiO₂ not exceeding 1.25 ppm are used (prior to the bend inthe curve).

A desired concentration of TiO2 may be calculated as follows:

A trend line equation for an average amount of TiO₂ particles for agiven concentration is:

Y (particles 2-3 micron)=276,558×X (Desired TiO2 Concentration)

The number of particles required for 6.5 Log challenge is: 6.5 Logparticles=3,162,278 particles. Therefore the required markerconcentration is: 3,162,278 particles/276,558=11.43 ppm (Desired TiO₂Concentration). To achieve a 6.5 Log particles/100 ml we must add 11.43ppm of TiO₂ powder to the concentrate side of the membrane. To beconservative the value will be rounded up to 12 ppm. Therefore 12 gramsof TiO₂ may be required per 1000 liters of water.

Example 3: Marker Concentration

The following formula may be used to calculate an amount of TiO₂ neededin a given system for performing a marker based direct integritytesting:((12 grams TiO₂)/(1000 Liters))×water volume of loop (Liters)

Table 4 demonstrates amounts of TiO2 needed to be added to various watervolume amounts to achieve a 6.5 Log particles/100 mL.

TABLE 4 Amounts of TiO₂ Added Per Loop Volume Water Volume of CeramicUltra Amount TiO₂ Required Unit Size Filtration Concentrate Loop(Liters) (Grams) M16 505 6.06 M36 980 11.76 DM36 1870 22.44 M48 250030.00

What is claimed is:
 1. A method of marker based direct integrity testingof at least one membrane comprising: (a) dosing a feed fluid of a loopwith at least one marker comprising at least one solid challengeparticle to generate a dosed feed fluid, the loop comprising: a pumpcomprising an outlet stream and configured to regulate a flow of thedosed feed fluid to at least one membrane module; the at least onemembrane module comprising the at least one membrane and configured tofilter the dosed feed fluid to generate at least one of a filtratecomprising at least one filtered marker and a marker recycle stream,wherein the at least one membrane module is configured to operate at aflux from about 100 liters/m²/h to about 2,000 liters/m²/h during themethod of marker based direct integrity testing of a membrane; and ameans to measure a particle concentration of the at least one filteredmarker; (b) circulating the dosed feed fluid through the at least onemembrane module at least once to produce the filtrate; (c) measuring afiltrate particle concentration of the at least one filtered marker inthe filtrate to produce a filtrate concentration measurement; and (d)replacing the at least one membrane if the filtrate particleconcentration exceeds a threshold level.
 2. The method of marker baseddirect integrity testing of at least one membrane of claim 1, whereinthe at least one membrane comprises at least one ceramic membrane. 3.The method of marker based direct integrity testing of at least onemembrane of claim 2, wherein the at least one ceramic membrane isselected from the group consisting of TiO₂, ZrO₂, SiO₂, MnO₂, SiC, CuO,MgO, and Al₂O₃.
 4. The method of marker based direct integrity testingof at least one membrane of claim 1, wherein dosing the feed fluid of aloop with the at least one marker comprising the at least one solidchallenge particle comprises a concentration of the at least one markerof about 6.5 log particle count.
 5. The method of marker based directintegrity testing of at least one membrane of claim 1, wherein the atleast one challenge particle is TiO₂.
 6. The method of marker baseddirect integrity testing of at least one membrane of claim 5, whereinthe TiO₂ is a P25 TiO₂.
 7. The method of marker based direct integritytesting of at least one membrane of claim 1, wherein about 35% of the atleast one challenge particle by mass contains particles comprising aparticle size from about 2 μm to about 3 μm.
 8. The method of markerbased direct integrity testing of at least one membrane of claim 1,further comprising calculating a log removal value from the filtrateparticle concentration, wherein the log removal value is less than about3.
 9. A method of marker based direct integrity testing of at least onemembrane comprising: (a) isolating a loop from at least one portion of awater purification system, the loop comprising: a feed fluid; a pumpcomprising an outlet stream and configured to regulate a flow of the adosed feed fluid to at least one membrane module; the at least onemembrane module comprising the at least one membrane and configured tofilter the feed fluid to generate at least one of a filtrate and amarker recycle stream, wherein the at least one membrane module isconfigured to operate at a flux from about 100 liters/m²/h to about2,000 liters/m²/h during the method of marker based direct integritytesting of at least one membrane; and a means to measure a particleconcentration of at least one filtered marker; (b) dosing the feed fluidwith at least one marker comprising at least one solid challengeparticle to generate a the dosed feed fluid; (c) circulating the feedfluid through the membrane module at least once to produce a filtratecomprising a filtered at least one marker; (d) measuring a filtrateparticle concentration of the filtered at least one marker in thefiltrate to produce a filtrate concentration measurement; and (e)replacing the at least one membrane if the filtrate concentrationmeasurement exceeds a threshold level.
 10. The method of marker baseddirect integrity testing of at least one membrane of claim 9, whereinthe at least one membrane comprises at least one ceramic membrane. 11.The method of marker based direct integrity testing of at least onemembrane of claim 10, wherein the at least one ceramic membrane isselected from the group consisting of TiO₂, ZrO₂, SiO₂, MnO₂, SiC, CuO,MgO, and Al₂O₃.
 12. The method of marker based direct integrity testingof at least one membrane of claim 9, wherein the feed particleconcentration of the at least one marker in the feed fluid is about 6.5log particle count.
 13. The method of marker based direct integritytesting of at least one membrane of claim 9, wherein the at least onesolid challenge particle is a TiO₂.
 14. The method of marker baseddirect integrity testing of at least one membrane of claim 13, whereinthe TiO₂ is a P25 TiO₂.
 15. The method of marker based direct integritytesting of at least one membrane of claim 9, wherein about 35% of the atleast one challenge particle by mass contains particles comprising aparticle size from about 2 μm to about 3 μm.
 16. The method of markerbased direct integrity testing of at least one membrane of claim 9,further comprising calculating a log removal value from the filtrateconcentration measurement, wherein the log removal value is less thanabout 3.